Hi,
Unfortunately, parts for a 94 Voyager are no longer in stock, cannot be ordered, and will not be retrofitted by the dealer. You definitely shouldn't use a vehicle-specific part for a different vehicle as they have different structural specs and requirements.
The available options in this situation are:
1. Rear-face children until an appropriate age, weight and height to use a booster seat.
2. Install a generic tether anchor manufactured by a child restraint manufacturer instead. Most only officially approve use with their own seats. If you can't find one made by your seat manufacturer, you can consider the risks and benefits of using another. Ez-On has approved using theirs with other seats on a case-by-case basis as long as the overall weight limit of 168 lbs child plus seat is not exceeded; their heavy duty tether anchor can be ordered through bus parts distributors.
3. "Temporary tethering" to an unused seatbelt behind the seating position is an option in 3 row vehicles in some cases. It is not always an approved solution; however it is a tested solution. As a stopgap measure it's a choice I've made myself a few times until a better solution could be found.
Good luck with your decision-making and let us know if we can answer questions about any of these options.